[PATCH 153/163] drm/i915: Implement eviction locking v2
Matthew Auld
matthew.auld at intel.com
Mon Nov 23 11:10:23 UTC 2020
From: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
Use a separate acquire context list and a separate locking function
for objects that are locked for eviction. These objects are then
properly referenced while on the list and can be unlocked early in
the ww transaction.
Co-developed-by: Thomas Hellström <thomas.hellstrom at linux.intel.com>
Signed-off-by: Thomas Hellström <thomas.hellstrom at linux.intel.com>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
Cc: Matthew Auld <matthew.auld at intel.com>
---
drivers/gpu/drm/i915/gem/i915_gem_object.h | 67 +++++++++++++++++--
.../gpu/drm/i915/gem/i915_gem_object_types.h | 5 ++
drivers/gpu/drm/i915/gem/i915_gem_shrinker.c | 14 +++-
drivers/gpu/drm/i915/i915_gem_ww.c | 51 ++++++++++----
drivers/gpu/drm/i915/i915_gem_ww.h | 3 +
5 files changed, 122 insertions(+), 18 deletions(-)
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.h b/drivers/gpu/drm/i915/gem/i915_gem_object.h
index 52a36b4052f0..e237b0fb0e79 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_object.h
+++ b/drivers/gpu/drm/i915/gem/i915_gem_object.h
@@ -158,6 +158,32 @@ static inline void assert_object_held_shared(struct drm_i915_gem_object *obj)
assert_object_held(obj);
}
+static inline int
+i915_gem_object_lock_to_evict(struct drm_i915_gem_object *obj,
+ struct i915_gem_ww_ctx *ww)
+{
+ int ret;
+
+ if (ww->intr)
+ ret = dma_resv_lock_interruptible(obj->base.resv, &ww->ctx);
+ else
+ ret = dma_resv_lock(obj->base.resv, &ww->ctx);
+
+ if (!ret) {
+ list_add_tail(&obj->obj_link, &ww->eviction_list);
+ i915_gem_object_get(obj);
+ obj->evict_locked = true;
+ }
+
+ GEM_WARN_ON(ret == -EALREADY);
+ if (ret == -EDEADLK) {
+ ww->contended_evict = true;
+ ww->contended = i915_gem_object_get(obj);
+ }
+
+ return ret;
+}
+
static inline int __i915_gem_object_lock(struct drm_i915_gem_object *obj,
struct i915_gem_ww_ctx *ww,
bool intr)
@@ -169,13 +195,25 @@ static inline int __i915_gem_object_lock(struct drm_i915_gem_object *obj,
else
ret = dma_resv_lock(obj->base.resv, ww ? &ww->ctx : NULL);
- if (!ret && ww)
+ if (!ret && ww) {
list_add_tail(&obj->obj_link, &ww->obj_list);
- if (ret == -EALREADY)
- ret = 0;
+ obj->evict_locked = false;
+ }
- if (ret == -EDEADLK)
+ if (ret == -EALREADY) {
+ ret = 0;
+ /* We've already evicted an object needed for this batch. */
+ if (obj->evict_locked) {
+ list_move_tail(&obj->obj_link, &ww->obj_list);
+ i915_gem_object_put(obj);
+ obj->evict_locked = false;
+ }
+ }
+
+ if (ret == -EDEADLK) {
+ ww->contended_evict = false;
ww->contended = i915_gem_object_get(obj);
+ }
return ret;
}
@@ -580,6 +618,27 @@ i915_gem_object_invalidate_frontbuffer(struct drm_i915_gem_object *obj,
__i915_gem_object_invalidate_frontbuffer(obj, origin);
}
+/**
+ * i915_gem_get_locking_ctx - Get the locking context of a locked object
+ * if any.
+ *
+ * @obj: The object to get the locking ctx from
+ *
+ * RETURN: The locking context if the object was locked using a context.
+ * NULL otherwise.
+ */
+static inline struct i915_gem_ww_ctx *
+i915_gem_get_locking_ctx(const struct drm_i915_gem_object *obj)
+{
+ struct ww_acquire_ctx *ctx;
+
+ ctx = obj->base.resv->lock.ctx;
+ if (!ctx)
+ return NULL;
+
+ return container_of(ctx, struct i915_gem_ww_ctx, ctx);
+}
+
#ifdef CONFIG_MMU_NOTIFIER
static inline bool
i915_gem_object_is_userptr(struct drm_i915_gem_object *obj)
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object_types.h b/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
index 331d113f7d5b..c42c0d3d5d67 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
+++ b/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
@@ -142,6 +142,11 @@ struct drm_i915_gem_object {
*/
struct list_head obj_link;
+ /**
+ * @evict_locked: Whether @obj_link sits on the eviction_list
+ */
+ bool evict_locked;
+
/** Stolen memory for this object, instead of being backed by shmem. */
struct drm_mm_node *stolen;
union {
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_shrinker.c b/drivers/gpu/drm/i915/gem/i915_gem_shrinker.c
index 27674048f17d..59d0f14b90ea 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_shrinker.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_shrinker.c
@@ -100,6 +100,7 @@ i915_gem_shrink(struct i915_gem_ww_ctx *ww,
unsigned long *nr_scanned,
unsigned int shrink)
{
+ struct drm_i915_gem_object *obj;
const struct {
struct list_head *list;
unsigned int bit;
@@ -164,7 +165,6 @@ i915_gem_shrink(struct i915_gem_ww_ctx *ww,
*/
for (phase = phases; phase->list; phase++) {
struct list_head still_in_list;
- struct drm_i915_gem_object *obj;
unsigned long flags;
if ((shrink & phase->bit) == 0)
@@ -197,6 +197,10 @@ i915_gem_shrink(struct i915_gem_ww_ctx *ww,
if (!can_release_pages(obj))
continue;
+ /* Already locked this object? */
+ if (ww && ww == i915_gem_get_locking_ctx(obj))
+ continue;
+
if (!kref_get_unless_zero(&obj->base.refcount))
continue;
@@ -209,7 +213,11 @@ i915_gem_shrink(struct i915_gem_ww_ctx *ww,
if (!i915_gem_object_trylock(obj))
goto skip;
} else {
- err = i915_gem_object_lock(obj, ww);
+ err = i915_gem_object_lock_to_evict(obj, ww);
+ if (err == -EALREADY) {
+ err = 0;
+ goto skip;
+ }
if (err)
goto skip;
}
@@ -235,6 +243,8 @@ i915_gem_shrink(struct i915_gem_ww_ctx *ww,
if (err)
return err;
}
+ if (ww)
+ i915_gem_ww_ctx_unlock_evictions(ww);
if (shrink & I915_SHRINK_BOUND)
intel_runtime_pm_put(&i915->runtime_pm, wakeref);
diff --git a/drivers/gpu/drm/i915/i915_gem_ww.c b/drivers/gpu/drm/i915/i915_gem_ww.c
index 43960d8595eb..811bf7677d78 100644
--- a/drivers/gpu/drm/i915/i915_gem_ww.c
+++ b/drivers/gpu/drm/i915/i915_gem_ww.c
@@ -10,24 +10,45 @@ void i915_gem_ww_ctx_init(struct i915_gem_ww_ctx *ww, bool intr)
{
ww_acquire_init(&ww->ctx, &reservation_ww_class);
INIT_LIST_HEAD(&ww->obj_list);
+ INIT_LIST_HEAD(&ww->eviction_list);
ww->intr = intr;
ww->contended = NULL;
+ ww->contended_evict = false;
+}
+
+void i915_gem_ww_ctx_unlock_evictions(struct i915_gem_ww_ctx *ww)
+{
+ struct drm_i915_gem_object *obj, *next;
+
+ list_for_each_entry_safe(obj, next, &ww->eviction_list, obj_link) {
+ list_del(&obj->obj_link);
+ GEM_WARN_ON(!obj->evict_locked);
+ i915_gem_object_unlock(obj);
+ i915_gem_object_put(obj);
+ }
}
static void i915_gem_ww_ctx_unlock_all(struct i915_gem_ww_ctx *ww)
{
- struct drm_i915_gem_object *obj;
+ struct drm_i915_gem_object *obj, *next;
- while ((obj = list_first_entry_or_null(&ww->obj_list, struct drm_i915_gem_object, obj_link))) {
+ list_for_each_entry_safe(obj, next, &ww->obj_list, obj_link) {
list_del(&obj->obj_link);
+ GEM_WARN_ON(obj->evict_locked);
i915_gem_object_unlock(obj);
}
+
+ i915_gem_ww_ctx_unlock_evictions(ww);
}
void i915_gem_ww_unlock_single(struct drm_i915_gem_object *obj)
{
+ bool evict_locked = obj->evict_locked;
+
list_del(&obj->obj_link);
i915_gem_object_unlock(obj);
+ if (evict_locked)
+ i915_gem_object_put(obj);
}
void i915_gem_ww_ctx_fini(struct i915_gem_ww_ctx *ww)
@@ -39,27 +60,33 @@ void i915_gem_ww_ctx_fini(struct i915_gem_ww_ctx *ww)
int __must_check i915_gem_ww_ctx_backoff(struct i915_gem_ww_ctx *ww)
{
+ struct drm_i915_gem_object *obj = ww->contended;
int ret = 0;
- if (WARN_ON(!ww->contended))
+ if (WARN_ON(!obj))
return -EINVAL;
i915_gem_ww_ctx_unlock_all(ww);
if (ww->intr)
- ret = dma_resv_lock_slow_interruptible(ww->contended->base.resv, &ww->ctx);
+ ret = dma_resv_lock_slow_interruptible(obj->base.resv, &ww->ctx);
else
- dma_resv_lock_slow(ww->contended->base.resv, &ww->ctx);
+ dma_resv_lock_slow(obj->base.resv, &ww->ctx);
+ if (ret)
+ goto out;
/*
- * Unlocking the contended lock again, as might not need it in
- * the retried transaction. This does not increase starvation,
- * but it's opening up for a wakeup flood if there are many
- * transactions relaxing on this object.
+ * Unlocking the contended lock again, if it was locked for eviction.
+ * We will most likely not need it in the retried transaction.
*/
- if (!ret)
- dma_resv_unlock(ww->contended->base.resv);
+ if (ww->contended_evict) {
+ dma_resv_unlock(obj->base.resv);
+ } else {
+ obj->evict_locked = false;
+ list_add_tail(&obj->obj_link, &ww->obj_list);
+ }
- i915_gem_object_put(ww->contended);
+out:
+ i915_gem_object_put(obj);
ww->contended = NULL;
return ret;
diff --git a/drivers/gpu/drm/i915/i915_gem_ww.h b/drivers/gpu/drm/i915/i915_gem_ww.h
index f6b1a796667b..11793b170cc2 100644
--- a/drivers/gpu/drm/i915/i915_gem_ww.h
+++ b/drivers/gpu/drm/i915/i915_gem_ww.h
@@ -10,15 +10,18 @@
struct i915_gem_ww_ctx {
struct ww_acquire_ctx ctx;
struct list_head obj_list;
+ struct list_head eviction_list;
struct drm_i915_gem_object *contended;
unsigned short intr;
unsigned short loop;
+ unsigned short contended_evict;
};
void i915_gem_ww_ctx_init(struct i915_gem_ww_ctx *ctx, bool intr);
void i915_gem_ww_ctx_fini(struct i915_gem_ww_ctx *ctx);
int __must_check i915_gem_ww_ctx_backoff(struct i915_gem_ww_ctx *ctx);
void i915_gem_ww_unlock_single(struct drm_i915_gem_object *obj);
+void i915_gem_ww_ctx_unlock_evictions(struct i915_gem_ww_ctx *ww);
/* Internal functions used by the inlines! Don't use. */
static inline int __i915_gem_ww_fini(struct i915_gem_ww_ctx *ww, int err)
--
2.26.2
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